The overall goal of this research focuses on the evaluation of methods for the serodiagnosis of Brucella canis (B. canis) and the development of an antigen of improved specificity. Antigens currently available for serodiagnostic tests cross-react extensively with both known and unidentified rough (R) gram-negative bacteria and methods are empirical. Goals for the current year included a critical study of the comparative sensitivities of four methods, namely, a rapid slide agglutination test (SAT); a tube agglutination test (TAT); a 2-mercaptoethanol tube agglutination test (ME-TAT) and an agarose gel immunodiffusion method, using a sodium deoxycholate (SDE) cell wall extract as antigen. Additional studies dealt with comparisons of methods for the crude extraction of B. canis cell wall antigens suitable for AGD analysis using B. canis-specific antisera produced in SPF dogs. Also studied were antigenic extracts from a variety of gram-negative bacteria we have found to cross-react to varying degrees with B. canis. Antiserums raised against these organisms and antigens were compared using AGD and immunoelectrophoretic methods. Physical, chemical and biologic properties of the anitgenic extracts were investigated. Research in the coming year will focus on purification of R-lipopolysaccharide antigens of B. canis and an analysis of the normal and immune macrophage - B. canis interaction, using virulent and avirulent organisms.